NeXus is developed as an international standard by scientists and programmers representing major scientific facilities in Europe, Asia, Australia, and North America in order to facilitate greater cooperation in the analysis and visualization of neutron, x-ray, and muon data.

canSAS

Pete Jemian presented the canSAS application definition. There is a mapping from canSAS to NeXus.

There was some discussion on this. The result was that the definition will be revised to only represent the processed data (I(Q)) use case. To be revisited once this is done. May be tomorrow.

WWW-Site

Ray presented his suggestion for a revised NeXus WWW-site. The main point is to make it look more modern. Also it is to be generated with sphinx which makes it easier to restyle it using sphinx styles.

Still needs some work, revisit at NeXus Telco. Then make it mobile friendly. If we can do this easily with Sphinx.

Thursday afternoon

NXmx, NXtransformations

Herbert is presenting proposed changes for NXmx-1.5.

NXmx is adding a NXdetector_group for documenting detectors better to humans. They have funny detectors with segments which move diagonally with regards to the detector center.

Added an optional third detector dimension. This is a data organizational dimension.

There is some discussion about understanding this.

Changes in NXbeam for polychromatic beams in the application definition. As optional, added in order to be able to validate this.

Flux may need two values, NXbeam defines flux is flux per unit area. The additional flux is a rate: photons/second. To be called total_flux.

Adding incident_beam_size which is a 2 value array of FWHM (when gaussian) or a diameter (if it is a top hat) or 2 sizes for a rectangular beam.

Changes to NXmx accepted by consensus after a little discussion with no objection.

Herberts presents changes to NXtransformations.

Axis rotation ranges are being added. Crystallographers want that for emotional reasons. The use case is the oscillation method.

Under discussion this changed to:

These three proposals to change NXtransformations below where unanimously accepted for by vote:

AXIS_end

AXIS_increment_set. This is the set value for the oscillation range in an oscillation experiment.

The actual AXIS value is the start of the oscillation. This needs to be updated in the documentation.

The general axis is highly contentious and not very well understood. Herbert says that a general axis could also be expressed as a translation.

The end of this: Aaron and Herbert provide better documentation and examples. We also half agreed to drop the transformation_type attribute for the general axis. This will be deferred until we understand this better.

Dinner

Very nice dinner at taarnet.dk in a high security environment with x-ray.

Variable length strings

We accept both variable and fixed length strings, readers have to support both, 11 yes, 1 no

Versioning

Short discussion on the versioning proposal as presented by Mark Koennecke from the result of the code camp.

Herbert made the comment to improve the workflow in this way:

You make the change to NXDL and change the version in the NXDL file

You build a manual and commit it into the repository

Then you tag the git repository

The proposal was accepted on probation with 12 yes. To be revisited at the next NIAC in order to check if it works.

Adoption of NeXus

Convincing scientists

Pete: use it and make this public

Herbert: NeXus is required for performance, performance problems,

Eugen: users do not want it because analysis tools do not support it, the chicken-egg problem

Sociological problems: to slow, social problems with NIAC

From WWW-site point to tools which can plot NeXus, downloadable applications,

NexPy and DAWN as general plotting tools

Pipelines from raw data to processed data

We spend a good deal of time on raw data formats. This is used for archiving at facilities, not for data exchange.

Now we are at a place where we understand so much about data that no one else understands us any more.

Herberts recommends us to listen: where are the needs, Aaron seconds with the question: how we can I help you to solve your scientific problem?

Ray requests support for NeXpy

We ended the discussion on a time limit.

NXdata

The problem: required group, some cases where no sensible default plot can be provided.

Change the documentation: make it clear that NXdata should be there but can be omitted if no sensible plot can be provide,
12 yes.

2014 Attributes

Pete Jemian has a modified version of application definitions with the 2014 attributes applied. This is the signal, axes definitions as group attributes. When changing application definitions consider the code in that branch.